3412 Generator Set Caterpillar

The atmospheric pressure sensor provides the ECM with an atmospheric pressure signal. The ECM uses the signal to calibrate the inlet manifold pressure sensor. The information is also used to protect the engine. The ECM limits the fuel rate during high altitude conditions.

Table 1

J1939 Code and Description	Conditions which Generate this Code	System Response
100- Engine Oil Pressure : Low - most severe (3)	Oil pressure is lower than the specified pressure for at least 4 seconds. Engine power is reduced. A snapshot is triggered.	The code is logged. After 30 seconds, the ECM will shut down the engine if the "Engine Monitoring Mode" parameter is programmed to "Shut down".
100-3 Oil Pressure voltage high	The oil pressure signal is above 4.7 VDC for one second. Also, there are no sensor supply diagnostic codes.	The diagnostic code is active and logged.
100-4 Oil Pressure voltage low	The oil pressure signal is less than 0.5 VDC for one second. Also, there are no sensor supply diagnostic codes.	The diagnostic code is active and logged.
102-0 Engine Intake Manifold #1 Pressure : High - most severe (3)	The boost pressure is above the trip point for high boost pressure.	The diagnostic code is active and logged.
102-1 Engine Intake Manifold #1 Pressure : Low - most severe (3)	The boost pressure is below the trip point for high boost pressure.	The diagnostic code is logged and the engine is derated.
102-03 Boost Pressure voltage high	The boost pressure sensor signal is greater than 5.0 VDC for one second. Also, there are no sensor supply diagnostic codes.	The diagnostic code is active and logged. The ECM sets the boost pressure to 600 kPa (87 psi). Engine power is limited.
102-04 Boost Pressure voltage low	The boost pressure sensor signal is less than 0.75 VDC for one second. Also, there are no sensor supply diagnostic codes.	The diagnostic code is active and logged. The ECM sets the boost pressure to 600 kPa (87 psi). Engine power is limited.
106-01 Engine Air Inlet Pressure : Low - most severe (3)	The atmospheric pressure is valid, but the pressure is below 0.68 VDC. This is a normal occurrence at altitudes above 1500 m (4921 ft).	The diagnostic code is logged. Also, the low oil pressure lamp is illuminated. The low atmospheric pressure or the high altitude derate is active.
106-03 Engine Air Inlet Pressure : Voltage Above Normal	Voltage is above 4.8 VDC for one second.	The diagnostic code is active and logged. The ECM will use a default value of 100 kPa (14.5 psi). This value will also be displayed on an electronic service tool.
106-04 Engine Air Inlet Pressure : Voltage Below Normal	The atmospheric pressure signal voltage is less than 0.2 VDC for at least one second.	The diagnostic code is active and logged. The ECM will use a default value of 100 kPa (14.5 psi). This value will also be displayed on an electronic service tool.
108-03 Barometric Pressure : Voltage Above Normal	Voltage is above 4.8 VDC for one second.	The diagnostic code is active and logged. The ECM will use a default value of 100 kPa (14.5 psi). This value will also be displayed on an electronic service tool.
108-04 Barometric Pressure : Voltage Below Normal	The atmospheric pressure signal voltage is less than 0.2 VDC for at least one second.	The diagnostic code is active and logged. The ECM will use a default value of 100 kPa (14.5 psi). This value will also be displayed on an electronic service tool.
110-00 Engine Coolant Temperature : High - most severe (3)	The coolant temperature is above the trip point.	The code is active and the code is logged.
110-03 Coolant Temperature voltage high	Voltage is above 4.7 V.	The diagnostic code is logged. The coolant temperature is set to a default of 0° C (32° F).
110-04 Coolant Temperature voltage low	Voltage is less than 0.3 V.	The code is logged and the alarm is activated.
678-03 ECU 8 Volts DC Supply : Voltage Above Normal	The 8 VDC supply to the sensor has been lost.	The code is active and the code is logged. All sensors are set to default values.
678-04 ECU 8 Volts DC Supply : Voltage Below Normal	The 8 VDC supply to the sensor has been lost.	The code is active and the code is logged. All sensors are set to default values.
3509-00 5 Volt Open Circuit	The 5 VDC supply to the sensor has been lost.	The code is active and the code is logged. All sensors are set to default values.
3509-01 5 Volt Short Circuit	The 5 VDC supply to the sensor has been lost.	The code is active and the code is logged. All sensors are set to default values.
3510-00 5 Volt Open Circuit	The 5 VDC supply to the sensor has been lost.	The code is active and the code is logged. All sensors are set to default values.
3510-01 5 Volt Short Circuit	The 5 VDC supply to the sensor has been lost.	The code is active and the code is logged. All sensors are set to default values.

Illustration 1	g03845003

Table 2

Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the Wiring Harness. A. Remove electrical power from the ECM. B. Thoroughly inspect the connector for the atmospheric pressure sensor and the J1/P1 connector. Inspect the ECM connector J2/P2. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. C. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the atmospheric pressure sensor. D. Check the allen head screw on the ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.	Electrical connectors and wiring	Result : The electrical connectors and wiring are OK. Proceed to Test Step 2. Result : The electrical connectors and/or wiring is NOT OK. Repair : Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem. If the problem is not resolved, proceed Test Step 2.
2. Check for Active Open or Short Diagnostic Codes. A. Connect Cat® Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools". B. Turn the engine control switch to the ON position. The engine should remain off. C. Check for active diagnostic codes listed in Table 1.	Diagnostic codes	Result : There are no diagnostic codes. Proceed to Test Step 3. Result : There is a short circuit. Proceed to Test Step 4. Result : There is an open circuit. Proceed to Test Step 3.
3. Check for Opens in the Wiring. A. Remove electrical power from the ECM. B. Disconnect the J2/P2 ECM connector and the connector for the atmospheric pressure sensor. C. Measure the resistance between the following terminals: - P2-17 to pin J15-A on the connector for the barometric pressure sensor - P2-10 to pin J15-B on the connector for the barometric pressure sensor P2-38 to pin J15-C on the connector for the barometric pressure sensor	Wiring	Result : The wiring is OK. Proceed to Test Step 4. Result : The wiring is NOT OK. Repair : Repair the circuit. If the problem is not resolved, proceed Test Step 4.
4. Check the Wiring for a Short Circuit. A. Measure the resistance between the following terminals: Note : Wiggle the harness during the following measurements in order to reveal an intermittent condition. - P14-30 (ECM connector) to pin J15-B and pinP14-30 (ECM connector) to J15-C on the connector for the atmospheric pressure sensor - P14-35 (ECM connector) to pin J15-C and P14-35 (ECM connector) to pin J15-A on the connector for the atmospheric pressure sensor - P14-34 (ECM connector) to pin J15-B and P14-34 (ECM connector) to pin J15-A on the connector for the atmospheric pressure sensor	Wiring	Result : The wiring is OK. Proceed to Test Step 5. Result : The wiring is NOT OK. Repair : Repair the wire and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved. If the problem is not resolved, proceed Test Step 5.
5. Check the Supply Voltage at the Sensor Connector. A. Disconnect the atmospheric pressure sensor. B. Restore electrical power to the ECM. C. Measure the voltage between terminals (A) and ( B) at the harness connector for the barometric pressure sensor. D. Remove electrical power from the ECM.	Voltage	Result : The voltage is OK. Proceed to Test Step 7. Result : The voltage is NOT OK. Proceed to Test Step 6.
6. Check the +5 V or +8 V Supply Voltage at the ECM. A. Remove electrical power from the ECM. B. Disconnect the J14/P14 ECM connector. C. Fabricate a wire jumper that is long enough to be used to measure the supply voltage at the ECM connector. Crimp a connector socket to one end of the wire. D. Remove the wire from terminal location P2-17(+5V) or P1-18(+8V). Install a wire jumper into the socket P2-17(+5V) or P1-18(+8V). E. Connect the J2/P2 ECM connector. F. Restore electrical power to the engine ECM. G. Measure the voltage between the wire jumper in P2-17 and engine ground. H. Remove electrical power from the ECM. I. Remove the wire jumper and replace all wires.	Voltage	Result : The voltage is OK. Proceed to Test Step 7. Result : The voltage is NOT OK. Repair : Replace the ECM. Refer to Troubleshooting, "ECM - Replace".
7. Check for Signal Voltage at the Sensor. A. Measure the voltage between P2/B (+5V) or P1-10 (+8V) and P2/C (+5V) or P1-50(+8V).	Voltage	Result : The voltage is between 1.6 VDC and 4.8 VDC. Repair : Repair the signal wire if the voltage is not present. If the problem is not resolved, proceed to Test Step 8.
8. Test the Operation of the ECM. A. Fabricate jumper wires that can be used to replace the signal wire in the ECM connector for the suspect sensor. Crimp a connector socket to one end of the jumper wire. B. Disconnect the ECM connector for the suspect sensor. C. Remove the signal wire for the suspect sensor from the ECM connector. D. Install the jumper wire into the terminal location for the suspect sensor at the ECM connector. E. Connect the ECM connector. F. Check the operation of the ECM by creating an open at the ECM. 1. Hold the loose end of the jumper wire away from any components in order to create an open circuit condition. 2. Turn the engine control switch to the ON position. 3. Monitor the active diagnostic code screen on Cat ET. Check for a 03 diagnostic code for the suspect sensor. Note : Wait at least 30 seconds in order for the diagnostic codes to become active. G. Check the operation of the ECM by creating a short circuit at the ECM. 1. Short the jumper wire for the suspect sensor to the analog return in order to create a short circuit condition. 2. Short the jumper wire for the suspect sensor to the analog return in order to create a short circuit condition. Note : Wait at least 30 seconds in order for the diagnostic codes to become active. H. Turn the engine control switch to the OFF position. I. Remove all jumper wires. Return the wiring to the original configuration.	ECM	Result : The ECM is OK. Repair : If the code is active for more than one sensor, the problem is most likely in the return wire for the sensor. Repair the analog return wire for the sensor or replace the harness. If the code is only active for one sensor, the problem is most likely in the signal wire for the sensor. Repair the signal wire for the sensor. Result : The ECM is NOT OK. Repair : Replace the ECM. Refer to Troubleshooting, "ECM - Replace". Verify that the problem is resolved.